Pressure measuring arrangements are well known in industrial process measurements technology. They serve in various embodiments for determining pressure of a process medium. Known pressure measuring arrangements of this type comprise a platform, which can also be a flange, and a thereon secured membrane, more specifically a measuring membrane, which is deformed in the direction of the platform by applied pressure of the process medium. A stroke of the membrane arising in such case is sensed by suitable techniques, usually electrically, and provides a measure for the applied pressure. The pressure measuring cell works thus as a pressure transducer. Flanges serving as platform of a pressure measuring cell are significantly larger than the pressure measuring cell itself.
In case the actual measuring membrane of the pressure measuring cell should not itself be exposed to the process medium to be measured, either because the process medium is chemically very aggressive or because it has a very high temperature, a pressure transfer means is used, which senses the pressure of the process medium and transmits such to the actual pressure transducer. Such pressure transfer means frequently comprise likewise a diaphragm carrier, comparable the above mentioned platform, on which also a membrane, also called an isolating diaphragm, is secured, which comes in contact with the process medium to be measured. An intermediate space between the isolating diaphragm and the diaphragm carrier is connected with a liquid filled, capillary line, so that the pressure of the process medium applied to the isolating diaphragm is transmitted to a pressure measuring cell connected with the capillary line.
It has been found in practice that materials directly in contact with the process medium, be it the material of the membrane of a pressure measuring cell or of such a pressure transfer means, must be manufactured of a special material, since it must withstand aggressive process media or frequently also aggressive cleaning methods used for pipelines and containers. The same holds, in principle, also for the side of flanges that contact the process medium. Manufacturing a total flange of a special material is, however, very costly and makes pressure measurement cells, or pressure transfer means with such flanges as platform, more expensive.